The present invention relates to a toner, composed of a plurality of mother particles and a plurality of external additive particles such as particles of silica, for developing an electrostatic latent image formed on a latent image carrier, and to an image forming apparatus for forming an image using the toner.
More particularly, the present invention relates to a toner, in which at least a plurality of particles of silica are used as an external additive and which has a function of preventing filming of toner to toner-contact members such as a latent image carrier, a toner carrier, and a toner regulating member, with which the toner may come in contact, thereby improving the durability of toner-contact members and also allowing the low-temperature fixing to be conducted well.
Further, the present invention relates to a toner in which at least a plurality of particles of titanium oxide or particles of alumina are used as an external additive and which is capable of stabilizing the charging property of toner, and to an image forming apparatus using this toner.
In an image forming apparatus using a toner, an image is obtained by developing an electrostatic latent image on a latent image carrier by a toner, transferring the developed image from the latent image carrier to a recording media such as paper to form a transferred image of the electrostatic latent image exposed on the latent image carrier, and finally fixing the transferred image to the recording media.
Among conventional image forming apparatuses, there is a multicolor image forming apparatus of intermediate transfer type as shown in FIG. 1. In an image forming apparatus 1 of this type, an image is exposed to light as an electrostatic latent image onto a photoreceptor 2 as a latent image carrier. The electrostatic latent image on the photoreceptor 2 is developed by yellow, magenta, cyan, and black non-magnetic mono-component developing devices 3, 4, 5, 6 in this order (the order of respective colors is arbitrary) so as to obtain visible developed images. The developed images on the photoreceptor 2 are superposed and toned on an intermediate transfer belt 7a of an intermediate transfer member 7, thus achieving primary transfer. After the primary transfer, the toned image is transferred to a recording media 9 such as a paper on a secondary transfer roller 8a of the transferring device 8, thus achieving secondary transfer. After that, the image is heated and fixed to the recording media 9 by a fixing device 10, thereby obtaining a desired image on the recording media 9.
Then, residual toner particles Txe2x80x2 remaining on the photoreceptor 2 after the developed images are transferred to the intermediate transfer belt 7a are removed by a cleaning blade 11 and are collected in a residual toner box 12. Similarly, residual toner particles remaining on the intermediate transfer belt 7a after the primary transferred image is transferred to the recording media 9 are removed by a cleaning blade and are collected in a residual toner box.
The respective non-magnetic mono-component developing devices 3, 4, 5, have substantially the same structure. That is, each of the developing devices 3, 4, 5, 6 is of a contact developing type that a conductive developing roller 16 is arranged in contact with the photoreceptor 2. As shown in FIG. 2(a), toner particles T in a toner container 13 are carried by a toner carrying means 14 to a toner supply roller 15 as toner supply means and is further supplied to the developing roller 16 by the toner supply roller 15. Accordingly, the toner particles T are held on the surface of the developing roller 16. A bias voltage composed of an alternating current superimposed on a direct current is applied to the developing roller 16 and the developing roller 16 is rotated at a high speed, whereby the toner particles T are regulated to be in a uniform thin layer by a toner regulating member 17 as toner regulating means, which is in press contact with the surface of the developing roller 16, and are uniformly charged. After that, the toner particles T on the developing roller 16 are uniformly conveyed toward the photoreceptor 2 which is in contact with the developing roller 16.
The toner particles T on the developing roller 16 is transferred to the photoreceptor 2 by developing voltage applied to the developing roller 16, whereby an electrostatic latent image is developed with the toner particles T on the photoreceptor 2.
The non-magnetic mono-component developing method employing conductive developing roller 16 also includes a non-contact developing method in which the developing roller 16 and a photoreceptor 2 are spaced apart from each other. In developing of the non-contact developing method, a developing voltage is applied to the developing roller 16 and toner particles T on the developing roller 16 is transferred by jumping to the photoreceptor 2 due to the developing voltage. That is, an electrostatic latent image on the photoreceptor 2 is developed with the toner particles T by jumping-developing.
In the conventional non-magnetic mono-component developing device, some toner particles T may be fused to toner-contact members, with which the toner may come in contact, such as the developing roller 16, the toner regulating blade 17, and/or the photoreceptor 2 or, alternatively, liberated external additive particles may be separated from the toner particles, thus leading to the occurrence of filming. Due to the filming, the insufficiency of toner carrying function of the developing roller 16, the insufficiency of regulating function of the toner regulating blade 17, and/or the insufficiency of developing function of the photoreceptor 2 may be occurred, thus further leading to degradation of image quality.
When the toner particles T are not uniformly charged, the insufficiency of toner carrying function of the developing roller 16, and/or the insufficiency of developing function of the photoreceptor 2 may be similarly occurred, thus further leading to similar problems.
To solve these problems, conventionally, resin mother particles 18 of the toner T are coated with external additive particles 19 as shown in FIG. 2(b). The size of the external additive particles 19 is set to be significantly smaller than the size of the mother particles 18.
Since use of a fixing device 10 for heat fixing enables the low-temperature fixing, conventionally, the mother particles 18 of the toner T have a low softening point so that the mother particles 18 are soft even at ordinary temperature.
On the other hand, in the conventional non-magnetic mono-component developing device, at least silica (SiO2) 19 is added as the external additive 19 in order to prevent the occurrence of the filming.
Further, in the non-magnetic mono-component developing device, titanium oxide (TiO2) 19 is added as the external additive 19 serving as a charge controlling agent as shown in FIG. 2(b) in order to stabilize the charge of the toner T.
Furthermore, in the non-magnetic mono-component developing device, alumina (Al2O3) 19 is added as the external additive 19 serving as a charge controlling agent and a cleaner as shown in FIG. 2(b) in order to stabilize the charge of the toner T and to clean the photoreceptor 2.
Particularly, most of conventional color toners employ a combination of silica and titanium oxide.
By the way, as for the aforementioned toner T, the external additive particles 19 adhere to the mother particles 18 by agitating the mother particles 18 and the external additive particles 19. As shown in FIG. 2(b), actually there are mother particles 18 and external additive particles 19 which adhere to each other (it should be noted that the numeral 18 is used for designating mother particles themselves as described above and also designating mother particles to which external additive particles 19 adhere and that the numeral 19 is used for designating external additive particles themselves as described above and also designating external additive particles adhering to mother particles), liberated mother particles 18xe2x80x2 to which no external additive particle 19 adheres, and liberated external additive particles 19xe2x80x2 adhering no mother particle 18 and they exist in the mixed state.
However, particularly for mother particles 18 having a low softening point, since the mother particles 18 are relatively soft, when the rate of the liberated mother particles 18xe2x80x2 in the toner T are increased, the liberated mother particles 18xe2x80x2 are fused to the aforementioned toner-contact members, thus facilitating the occurrence of filming and thus reducing the durability of the toner-contact members.
It may be considered to increase the adding amount of the external additive particles 19 to reduce the amount of the liberated mother particles 18xe2x80x2. When silica (SiO2) 19 is employed as the external additives, the increase in the amount of silica particles 19 facilitates silica particles 19 to enter in the mother particles 18 because the mother particles 18 are relatively soft. When the silica particles 19 enter in the mother particles 18, the effect of the silica particles 19 coating the mother particles 18 is reduced. Therefore, the toner particles T are fused onto the toner-contact members, thus facilitating the occurrence of filming and thus reducing the durability of the toner-contact members in the same manner as mentioned above.
In addition, as the adding amount of silica particles 19 is increased, the amount of liberated silica particles 19xe2x80x2 as the liberated external additives 19xe2x80x2 is also increased. Therefore, the liberated silica particles 19xe2x80x2 may adhere to the toner-contact members, thus also leading to the occurrence of filming.
Moreover, as the amount of silica particles 19 is increased, not only a large quantity of heat for heat fixing is consumed by the silica particles 19, but also heat is hard to be transferred to the mother particles 18 because the mother particles 18 are coated with many silica particles 19. As a result, it is easy to be subjected to deterioration of low-temperature fixing property. In addition, the coating on the mother particles 18 by the silica particles 19 blocks the elution of releasing agent, thus leading to the deterioration of fixing property.
When titanium oxide 19 is employed as the external additive 19 in the toner T (it should be noted that the numeral 18 is used for designating mother particles themselves as described above and also designating mother particles to which titanium oxide particles 19 adhere and that the numeral 19 is used for designating titanium oxide particles themselves as described above and also designating titanium oxide particles adhering to mother particles), the titanium oxide particles 19 adhere to the mother particles 18 by mixing or agitating the mother particles 18 and the titanium oxide particles 19. As shown in FIG. 2(b), actually there are mother particles 18 and titanium oxide particles 19 which adhere to each other, liberated mother particles 18xe2x80x2 to which no titanium oxide particle 19 adheres, and liberated titanium oxide particles 19xe2x80x2 adhering no mother particle 18 and they exist in the mixed state.
However, the increase in the amount of liberated mother particles 18xe2x80x2 leads to excessive charge due to liberated mother particles 18xe2x80x2, thus producing the insufficiency of development.
It may be considered to increase the adding amount of the titanium oxide particles 19 to reduce the amount of the liberated mother particles 18xe2x80x2. However, the increase in the amount of titanium oxide particles 19 leads to insufficient charge, thus bringing about image defects and toner scattering.
In addition, as the adding amount of titanium oxide particles 19 is increased, the amount of liberated titanium oxide particles 19xe2x80x2 is also increased. Therefore, the liberated titanium oxide particles 19xe2x80x2 may adhere to the toner-contact members, thus facilitating the occurrence of filming.
When alumina 19 is employed as the external additive 19 in the toner T (it should be noted that the numeral 18 is used for designating mother particles themselves as described above and also designating mother particles to which alumina particles 19 adhere and that the numeral 19 is used for designating alumina particles themselves as described above and also designating alumina particles adhering to mother particles), the alumina particles 19 adhere to the mother particles 18 by mixing or agitating the mother particles 18 and the alumina particles 19. As shown in FIG. 2(b), actually there are mother particles 18 and alumina particles 19 which adhere to each other, liberated mother particles 18xe2x80x2 to which no alumina particle 19 adheres, and liberated alumina particles 19xe2x80x2 adhering no mother particle 18 and they exist in the mixed state.
However, as mentioned above, the increase in the amount of liberated mother particles 18xe2x80x2 in the toner T leads to excessive charge due to liberated mother particles 18xe2x80x2, thus producing the insufficiency of development. For this, it may be considered to increase the adding amount of the alumina particles 19 to reduce the amount of the liberated mother particles 18xe2x80x2. However, since the increase in the amount of alumina particles 19 increases the amount of liberated alumina particles 19xe2x80x2, the liberated alumina particles 19xe2x80x2 adhere to the toner-contact members, thus facilitating the occurrence of filming.
In addition, since the alumina 19 has a function of controlling the charging property of the toner, the increase in the amount of alumina particles 19 deteriorates the charging property of the toner.
On the other hand, conventional toners include polymerized toners which are prepared by a polymerization method and pulverized toners which are prepared by a pulverization method and are rounded by heat treatment. Mother particles of these toners have relatively large roundness of 0.95 or more and are approximately formed in spheres. In the mother particles 18 having a low softening point particularly, the larger the roundness of a mother particle 18 is, the more spherical the mother particle 18 is. In this state, the mother particles 18 of the residual toner Txe2x80x2 remaining on the photoreceptor 2 or the intermediate transfer belt 7a after transferred may pass through a space between the cleaning blade 11 and the photoreceptor 2 or between the cleaning blade 11 and the intermediate transfer belt 7a, that is, may not be removed by the cleaning blade 11, thus deteriorating the cleaning property of the cleaning blade 11. As a result of this, these particles remain adhering to the photoreceptor 2 and/or the intermediate transfer belt 7a, thus leading to the occurrence of filming. This reduces the durability of the photoreceptor 2 and the intermediate transfer belt 7a as the toner-contact members.
As the amount of liberated external additive particles 19xe2x80x2 in the toner T is increased, it is difficult to effectively coat the mother particles 18 with the external additive particles 19. Accordingly, as mentioned above, the mother particles 18 are easily fused on the toner-contact members, thus facilitating the occurrence of filming. In addition, liberated external additives 19xe2x80x2 easily adhere to the toner-contact members because the liberated external additive particles 19xe2x80x2 are many, thereby also facilitating the occurrence of filming and thus decreasing the durability of the toner-contact members.
Moreover, many liberated external additive particles 19xe2x80x2 easily soil the inside of each developing device 3, 4, 5, 6. Particularly, once charging members, such as the developing roller 16 and the toner regulating blade 17, for charging the toner T, are coated with the liberated external particles 19xe2x80x2, it is hard to charge the toner T, thereby reducing the charging property of the toner T.
When the amount of liberated external additive particles 19xe2x80x2 is small, not only a large quantity of heat for heat fixing is consumed by the external additive particles 19, but also heat is hard to be transferred to the mother particles 18 because the mother particles 18 are coated with many external additive particles 19. As a result, it is easy to be subjected to deterioration of low-temperature fixing property and the elution of releasing agent is blocked, thus leading to the deterioration of fixing property.
There is another problem that external additive particles may enter in mother particles so that components having low melting point of the mother particles soil the toner-contact members.
When the amount of liberated external additive particles 19xe2x80x2 is small, the liberated external additive particles 19xe2x80x2 can not exhibit the effect of cleaning the toner-contact members such as the photoreceptor 2 and the intermediate transfer belt 7a. 
Generally, there are a large number of mother particles 18 of which particle diameter is about 1.5 xcexcm or more. The smaller the particle diameter is, the lower the roundness of the mother particle 18 is. This is due to some problems on production of toners T such as in the pulverization method. With lower roundness, the mother particle 18 may have not only increased portions (e.g. sharp edges) to which the external additive particles 19 hardly adhere but also concaved portions in which the external additive particles 19 may enter, thereby hardly exhibiting the effect of the external additive particles 19.
As the amount of liberated mother particles 18xe2x80x2 in the toner T is increased, the liberated mother particles 18xe2x80x2 easily adhere to the toner-contact members. In addition, since the number of external additive particles 19 adhering to the mother particles 18 is reduced, the mother particles 18 not the liberated mother particles 18xe2x80x2 also easily adhere to the toner-contact members. As the mother particles 18 adhere to the toner-contact members, filming occurs on the toner-contact members, thus reducing the durability of the toner-contact members. The mother particles 18 having a low softening point especially easily adhere to the toner-contact members because of the mother particles 18 are relatively soft, thus facilitating the occurrence of filming on the toner-contact members. In addition, since micro particles as mother particles 18 adhering to the toner-contact members are further hardly removed, the possibility of occurrence of filming on the toner-contact members is increased.
When titanium oxide particles adhere to the mother particles 18 strongly in comparison to silica particles, the toner can not be charged uniformly, thus deteriorating the uniformity of charging. The reason why the uniformity of charging is deteriorated may be that the titanium oxide particles hardly move in comparison to the silica particles.
It is an object of the present invention to provide a toner, employing at least either of silica and titanium oxide as external additives, which is capable of effectively preventing the occurrence of filming on toner-contact members such as a toner carrier, a toner regulating member, and a latent image carrier and thus improving the durability of the toner-contact members and the toner charging property, and to provide an image forming apparatus employing this toner.
It is another object of the present invention to provide a toner which is capable of preventing the occurrence of filming on the toner-contact members and still achieving satisfactory low-temperature fixing, and to provide an image forming apparatus employing this toner.
It is further another object of the present invention to provide a toner, employing at least titanium oxide as an external additive, which has improved charging property, and to provide an image forming apparatus employing this toner.
It is still another object of the present invention to provide a toner, employing at least alumina as an external additive, which has improved stable charging property and is capable of effectively cleaning a latent image carrier, and to provide an image forming apparatus employing this toner.
It is yet another object of the present invention to provide a toner which is capable of providing satisfactory effect of cleaning toner-contact members as a result of liberated external additive particles even with mother particles having large roundness, and to provide an image forming apparatus employing this toner.
It is another object of the present invention to provide a toner which is capable of preventing the occurrence of filming on toner-contact members such as a toner carrier, a toner-regulating member, and a latent image carrier by achieving uniform adhesion of external additive particles to mother particles, which are micro particles, as possible, and to provide an image forming apparatus employing this toner.
It is another object of the present invention to provide a toner which is capable of preventing the occurrence of filming on toner-contact members such as a toner carrier, a toner regulating member, and a latent image carrier and capable of improving the charge uniformity and to provide an image forming apparatus employing this toner.
To achieve the aforementioned objects, a toner of the present invention comprises, at least, a plurality of mother particles and a plurality of silica particles, and is characterized in that the liberated mother particle ratio of liberated mother particles without silica particle adhering thereto is set to be 10% or less and the liberated silica particle ratio of liberated silica particles adhering to none of the mother particles is set to be 0.2-10%.
The toner of the present invention is characterized in that the silica particles are surface treated with HMDS.
Further, a toner of the present invention comprises, at least, a plurality of mother particles and a plurality of titanium oxide particles, and is characterized in that the liberated mother particle ratio of liberated mother particles without titanium oxide particle adhering thereto is set to be 30% or less and the liberated titanium oxide particle ratio of liberated titanium oxide particles adhering to none of the mother particles is set to be 5% or less.
Furthermore, a toner of the present invention comprises, at least, a plurality of mother particles and a plurality of alumina particles, and is characterized in that the liberated mother particle ratio of liberated Mother particles without alumina particle adhering thereto is set to be 30% or less and the liberated alumina particle ratio of liberated alumina particles adhering to none of the mother particles is set to be 0.2-5%.
Moreover, a toner of the present invention comprises, at least, a plurality of mother particles and a plurality of external additive particles in which the roundness of the mother particles is 0.95 or less, and is characterized in that the liberated external additive particle ratio of liberated external additive particles adhering to none of the mother particles is set to be 0.2-5%. The toner of the present invention is characterized in that said external additive particles are silica particles. In addition, the toner of the present invention is characterized in that said mother particles are pulverized toner particles prepared by the pulverization.
Further, a toner of the present invention comprises, at least, a plurality of mother particles and a plurality of external additive particles in which the roundness of the mother particles is 0.95 or more, and is characterized in that the liberated external additive particle ratio of liberated external additive particles adhering to none of the mother particles is set to be 3-10%. The toner of the present invention is characterized in that said external additive particles are silica particles. In addition, the toner of the present invention is characterized in that said mother particles are polymerized toner particles which are prepared by a polymerization method or pulverized rounded toner particles which are prepared by a pulverization method and processed by rounding treatment.
Furthermore, a toner of the present invention comprises, at least, a plurality of mother particles and a plurality of external additive particles, and is characterized in that the liberated mother particle ratio of liberated mother particles without external additive particle adhering thereto is set to be 15% or less, and the roundness of micro particles of 1.5-2.5 xcexcm in diameter as some of said mother particles is set to be 0.85-0.95. The toner of the present invention is characterized in that said external additive particles are silica particles.
Furthermore, a toner of the present invention comprises, at least, a plurality of mother particles and a plurality of external additive particles, and is characterized in that the external additive particles contain at least silica particles and titanium oxide particles, and said external additive particles are set such that the absolute deviation in synchronous distribution of said silica particles relative to said mother particles is smaller than the absolute deviation in synchronous distribution of said titanium oxide particles relative to said mother particles.
On the other hand, an image forming apparatus of the present invention comprises at least a latent image carrier on which an electrostatic latent image is formed; and a developing device having a toner carrier for carrying a toner to develop the electrostatic latent image on said latent image carrier, and a toner regulating means for at least regulating the toner to be carried toward said latent image carrier by said toner carrier, and is characterized in that said toner is a toner of the present invention as described above.
In the toner T of the present invention mentioned above, the liberated mother particle ratio is set to be 10% or less and the liberated silica particle ratio is set to be between 0.2% and 10%, the amount of liberated mother particles and the amount of liberated silica particles can be suitably set relative to the entire amount of the toner. As a result, the amount of the silica particles adhering to the mother particles is also suitably set, thereby reducing the possibility that the liberated mother particles, the liberated silica particles, and the mother particles with silica particles therein will be fused on the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member, and thus effectively preventing the filming of toner. Therefore, according to the toner of the present invention, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member can be improved and the image quality can be also improved.
Further, in the toner of the present invention, the amount of silica particles adhering to mother particles is suitable because the amount of liberated mother particles and the amount of liberated silica particles are suitably set, thereby preventing a large quantity of heat for heat fixing from being consumed by the silica particles. In addition, the mother particles are coated with a desired amount of silica particles, thus preventing the surfaces of the mother particles having a low melting point from being over-exposed. Therefore, according to the toner T of the present invention, the filming of the toner T onto the toner-contact members can be prevented and the low-temperature fixing property can be improved.
Furthermore, in the toner of the present invention, the silica particles are surface treated with HMDS so that the toner T has hydrophobic property. The hydrophobic property improves the fluidity of the toner like powder, thereby effectively preventing the occurrence of filming of the toner T.
In the toner of the present invention, the liberated mother particle ratio is set to be 30% or less and the liberated titanium oxide particle ratio is set to be 5% or less, whereby the amount of liberated mother particles and the amount of liberated titanium oxide particles can be suitably set relative to the entire amount of the toner. Therefore, the amount of the titanium oxide particles adhering to the mother particles is also suitably set so that excess charge of the liberated mother particles can be prevented and the charging property of the toner can be thus stabilized, thereby preventing the toner scattering and performing excellent development. As a result, high-quality images can be obtained.
In the toner of the present invention, the amount of the titanium oxide particles adhering to the mother particles is suitably set, thereby reducing the possibility that the liberated mother particles, the liberated titanium oxide particles, and the mother particles with titanium oxide particles therein will be fused on the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member, and thus effectively preventing the filming of toner. Therefore, according to the toner of the present invention, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member can be improved and the image quality can be also improved.
In the toner of the present invention, the liberated mother particle ratio is set to be 30% or less and the liberated alumina particle ratio is set to be 0.2-5%, whereby the amount of liberated mother particles and the amount of liberated alumina particles can be suitably set relative to the entire amount of the toner, thereby stabilizing the charging property of the toner, preventing the fogging, and yet allowing effective cleaning of the latent image carrier.
Further in the toner of the present invention, the amount of the alumina particles adhering to the mother particles is suitably set because the amount of liberated alumina particles is suitably set, thereby reducing the possibility that the liberated mother particles, the liberated alumina particles, and the mother particles with alumina particles therein will be fused on the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member, and thus effectively preventing the filming of toner. Therefore, according to the toner of the present invention, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member can be improved and the image quality can be also improved.
In the toner T of the present invention, the roundness of the mother particles is set to be 0.95 or less and the liberated additive particle ratio is set to be 0.2-5%, whereby the mother particles are not too spherical. Accordingly, mother particles of residual toner after transferred hardly pass below a cleaning blade so that the residual toner particles can securely removed by the cleaning blade. Therefore, the occurrence of filming on the toner-contact members can be prevented, thereby improving the durability of the toner-contact members which are cleaned by the cleaning blade.
Further in the toner of the present invention, since the amount of liberated external additive particles is suitably set relative to the entire amount of the toner, the mother particles can be effectively coated with the external additive particles, thereby preventing the occurrence of filming on the toner-contact members due to fusion of mother particles. Since the amount of liberated external additive particles is enough, the liberated external additive particles adhere to the toner-contact members, thus making the occurrence of filming difficult. This also improves the durability of the toner-contact members.
In addition, the inside of developing devices are hardly soiled by liberated external additive particles. Particularly, charging members, such as toner carriers, toner regulating members in the developing devices, for charging the toner are prevented from being coated with external particles, thereby facilitating charging of the toner and thus improving the charging property of the toner.
According to the toner T of the present invention, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member can be improved and high-quality images can be obtained.
In addition, in the toner of the present invention, the mother particles are effectively coated with external additive particles, thereby preventing a large quantity of heat for heat fixing from being consumed by the external additive particles. Therefore, heat can be effectively transferred to the mother particles, so that the low-temperature fixing property can be improved and the releasing agent can be suitably eluted from the toner, thereby improving the fixing property.
Moreover, in the toner of the present invention, even external additive particles embedded in mother particles, the mother particles are effectively coated with external additive particles, thereby preventing low-melting components of the mother particles from soiling the toner-contact members.
In the toner of the present invention, the liberated additive particle ratio is set to be 3-10% in the toner of which the roundness of the mother particles is 0.95 or more. Therefore, in a toner of which mother particles are nearly equal to the perfect sphere as a polymerized toner which is prepared by polymerization or a pulverized toner which is prepared by a pulverization and are rounded by heat treatment, the amount of liberated external additive particles can be suitably set relative to the entire amount of the toner. Accordingly, even in case of a toner with such mother particles which are nearly equal to the perfect sphere, enough cleaning effect for the toner-contact members such as a photoreceptor can be obtained because the liberated external additive particles work as a trigger, thereby improving the cleaning property.
Further in the toner of the present invention, since the amount of liberated external additive particles is suitably set relative to the entire amount of the toner, the mother particles can be effectively coated with the external additive particles so that the mother particles are hardly fused on the toner-contact members, thereby preventing the occurrence of filming on the toner-contact members. According to the toner of the present invention, the durability of the toner contact members such as the latent image carrier, the toner carrier, and the toner regulating member can be improved and high-quality images can be obtained.
In the toner of the present invention, the liberated mother particle ratio is set to be 15% or less in the toner of which the roundness of the micro particles of 1.5-2.5 xcexcm as mother particles is set to be between 0.85 and 0.95. Therefore, in a toner having a liberated mother particle ratio of 15% or less, the roundness of the micro particles as mother particles can be suitably highly set, thereby reducing possibility of fusion of liberated mother particles to the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member. In addition, uniform adhesion of external additive particles to the mother particles which are micro particles is achieved, thereby effectively reducing possibility of fusion of the micro particles as mother particles on the toner-contact members. As a result, the occurrence of filming on the toner-contact members is effectively prevented. According to the toner of the present invention, the durability of the toner contact members such as the latent image carrier, the toner carrier, and the toner regulating member can be improved and high-quality images can be obtained over a long period.
In the toner of the present invention, silica is used as the external additive and, in addition, a suitable amount of silica particles can adhere to the mother particles, thereby preventing a large quantity of heat for heat fixing from being consumed by the silica particles. In addition, the mother particles are coated with a desired amount of silica particles, thus preventing the surfaces of the mother particles having a low melting point from being over-exposed. Therefore, according to this toner, the filming of the toner onto the toner-contact members can be prevented and the low-temperature fixing property can be improved.
In the toner of the present invention, the external additive particles are set such that the absolute deviation in synchronous distribution of the silica particles relative to the mother particles is smaller than the absolute deviation in synchronous distribution of the titanium oxide particles relative to the mother particles, thereby effectively preventing the occurrence of filming on the toner-contact members such as the toner carrier, toner regulating member, and latent image carrier, because of the function of silica for preventing occurrence of filming. In addition, the distribution of the titanium oxide particles having a charge control function is set to be larger than the distribution of the silica particles so that the titanium oxide particles easily move, thereby achieving uniform charge of the toner T because of the function of the titanium oxide particles. According to the toner of the present invention, the filming on the toner contact members can be prevented and the charge uniformity of the toner can be improved.
On the other hand, in the image forming apparatus of the present invention, by using the toner in which the amount of liberated mother particles and the amount of liberated silica particles, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member are improved and high quality images can be obtained. In addition, since the surfaces of mother particles having a low melting point are hardly exposed, the image forming apparatus of the present invention can provide excellent low-temperature fixing property while preventing the filming of toner on the toner-contact members.
Further, in the image forming apparatus of the present invention, by using the toner in which the amount of liberated mother particles and the amount of liberated titanium oxide particles are suitably set relative to the entire amount of the toner as mentioned above, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member are improved and high quality images can be obtained, because the filming of toner is effectively prevented.
Furthermore, in the image forming apparatus of the present invention, by using the toner in which the amount of liberated mother particles and the amount of liberated alumina particles are suitably set relative to the entire amount of the toner as mentioned above, the latent image carrier can be effectively cleaned. In addition, because the filming of toner is effectively prevented, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member are improved and high quality images can be obtained.
Moreover, in the image forming apparatus of the present invention, by using a toner in which the roundness of the mother particles is set to be 0.95 or less and the liberated additive particle ratio is set to be 0.2-5%, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member are improved, the charging property of toner is improved, and high quality images can be obtained.
Further, in the image forming apparatus of the present invention, by using a toner in which the roundness of the mother particles is 0.95 or more and the liberated additive particle ratio is set to be 3-10%, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member are improved and high quality images can be obtained.
Furthermore, in the image forming apparatus of the present invention, by using a toner in which the liberated mother particle ratio is set to be 15% or less in the toner of which the roundness of the micro particles of 1.5-2.5 xcexcm as mother particles is set to be 0.85-0.95, the durability of the toner-contact members such as the latent image carrier, the toner carrier, and the toner regulating member are improved and high quality images can be obtained. In addition, because the surfaces of mother particles are hardly exposed so as to make heat hardly transferred to mother particles having a low melting point, the image forming apparatus of the present invention can prevent the occurrence of filming on the toner-contact members and yet obtaining excellent low-temperature fixing.
Moreover, in the image forming apparatus of the present invention, by using a toner in which the external additive particles are set such that the absolute deviation in synchronous distribution of the silica particles relative to the mother particles is smaller than the absolute deviation in synchronous distribution of the titanium oxide particles relative to the mother particles, the occurrence of filming on the toner-contact member in the apparatus can be prevented and the toner can be further uniformly charged, thereby obtaining high quality images.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.